Convertible couch or sofa frames which use pivoting seat and back supports are taught in U.S. Pat. Nos. 3,046,571; 4,321,716; and 5,103,510. However, these frames are for convertible couches and would not serve well as futon frames. The structure of these frames produces translational motion between the seat and the back which will interfere with the folding and extending of the futon. Furthermore, the linkage is complex and results in a complex multi-component frame.
Frames which do not produce translational motion between the seat and back during opening and closing are taught in U.S. Pat. No. 5,083,333 and co-pending application Ser. No. 08/054,897 of the present inventor. However, these patents teach frames which use locking hardware to directly lock the back to the seat member, stabilizing the back with respect to the seat in the closed position and the open position.
Frames which employ simpler linkages are also taught in U.S. Pat. Nos. 3,175,861; 4,205,405; and 4,217,669. While these patents teach simpler linkages, the resulting frame is not well suited to serve as a frame for a free standing conventional couch or sofa. The '861 patent is a convertible chair which can be placed in various positions but does not open to form a bed. Furthermore, the frame of the '861 patent requires locks to stabilize the chair in its alternate seating positions.
The '405 patent teaches a couch which converts to a bed; however, it teaches a frame that is secured to the surface on which it rests. The frame would also not be well suited for supporting a futon since the couch employs a padded back and seat and requires that a spacing pillow be placed between the back pad and the seat pad. These pads would be inconsistent with using the couch to support a futon. Furthermore, the couch is opened with a pull strap which would not be accessible with a futon in place.
The couch of the '669 patent has a frame which is again designed to be attached to the underlying surface on which it rests and without such attachment, the frame would be unstable, Furthermore, the design of the '669 patent leads to a frame constructed from tubular stock which is not well suited for fabrication from wood and does not provide supplemental support legs.
It should also be pointed out that neither the '405 patent nor the '699 patent teaches, discloses or claims couches which have arms as an integral part of their frames.
Futon frames with supplemental support legs attached to the seat of the futon frame provide additional support when the frame is open providing a sleeping surface. Many of these frames have concealable supplemental support legs which can be swung out of sight by the user when the frame is being closed. Typical patents that teach the use of concealable supplemental support legs which are pivotably attached to the seat of a frame are U.S. Pat. Nos. 4,642,823 and 5,083,333. While these patents teach frames with supplemental support legs attached to the seat of the frame, to position the supplemental support legs with respect to these frames requires that the legs be manually positioned by the user. Self positioning supplemental support legs are taught in U.S. Pat. Nos. 4,996,730 and 5,153,951. However, these legs must have a substantial setback from the front edge of the seat (at least the distance of the floor to seat distance) and thus are less effective in stabilizing the frame when in the open position.
Thus, there is a need for a frame which does not require a locking mechanism between the seat and back member which is suitable for use with a futon. There is also a need for an improved leg configuration for a futon frame which converts to a couch where the leg is both self concealing when stored and will provide a high degree of stability when the frame is opened to form a sleeping surface.